Xylem and Phloem

Functions of xylem and phloem

Vascular tissues are responsible for mass flow transport over long distances within a plant. They are split into two distinct systems:
- the xylem, which transports water and mineral ions from the roots up to the leaves and provides structural support to the plant due to its rigid walls
  - transportation is in one direction only. from roots via stem to leaves
- the phloem, which transports sucrose and amino acids from the source (where they are made or stored, like leaves) to the sink (where they are used or stored, like roots, flowers, and growing tips).
  - transportation is throughout the whole plant

Xylem. Phloem.

Xylem vessels are highly specialized dead cells that form a continuous piping system. Their structures directly enable efficient water transport.

Feature	Relating to function
Thick walls with lignin	Lignin makes the cell walls storng and waterproof, preventing vessles from collapsing inward under the extreme pressure (tension) created by transpiration, while also offering support to keep the plant upright.
No cell contents	The cells are dead and completely empty (no cytoplasm, nucleus, or organelles). This leaves a completely hollow central space (lumen) so water can flow freely with minimal resistance.
Joined end-to-end with no cross walls	Individual cells break down their end walls where they meet to form a long, continuous tube. This allows water columns to travel uninterrupted from the deepest roots all the way to the top of the leaves at the top.